Extensive research from Sweden, Finland, Denmark, and the United States reveals that homosexuality is primarily environmentally induced. Specifically, social and/or family factors, as well as permissive environments which affirm homosexuality, play major environmental roles in the development of homosexual behavior.

A closer look at the research

Twin study investigations of homosexuality were recently conducted in both Sweden and Finland. Such twin studies compare rates of homosexual behavior between different sibling groups who share varying degrees of genetic similarity (ie, identical twins versus non-identical twins). By comparing such rates, twin studies help sort out the extent to which homosexual behavior is genetic and/or environmental. For instance, if homosexuality is genetic, then in cases where one identical twin is homosexual the co-twin should be homosexual nearly 100 percent of the time because identical twins share 100 percent of their genes.

But that is not what these two large-scale Scandinavian studies found. Both studies revealed that when one identical twin was homosexual the other twin was homosexual only 10 percent or 11 percent of the time. Such findings indicate that homosexuality is not genetically determined.

A Danish research investigation studied two million adults living in Denmark, a country where same-sex marriage has been legal since 1989. This study uncovered a number of specific environmental factors that increase the probability an individual will seek a same-sex rather than an opposite-sex partner for marriage.

For Danish men, the environmental factors associated with higher rates of homosexual marriage include an urban birthplace and an absent or unknown father. Significantly, there was a linear relationship between degree of urbanization of birthplace and whether a man chose homosexual or heterosexual marriage as an adult. In other words, the more urban a man's birthplace, the more likely he was to marry a man, while the more rural a man's birthplace, the more likely he was to marry a woman.

For Danish women, the environmental factors related to increased likelihood of homosexual marriage include an urban birthplace, maternal death during adolescence, and mother-absence.

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Finally, an American research study—the most comprehensive and representative survey of sexual behavior in America—reported its findings concerning homosexuality. The results of this study also support an environmental theory of homosexuality, not a genetic one. In particular, this survey identified specific types of environments that increase the likelihood of homosexual behavior. The authors describe these environments as "congenial" to the development of homosexuality.

For American men, the environmental factor most related to homosexual behavior was the degree of urbanization during the teenage years. Specifically, boys who lived in large urban centers between the ages of 14 and 16 were three to six times more likely to engage in homosexual behavior than were boys who lived in rural communities during those same ages. The authors offer the following possibility: "an environment that provides increased opportunities for and fewer negative sanctions against same-gender sexuality may both allow and even elicit expression of same-gender interest and sexual behavior." Note the word "elicit." These researchers believe that growing up in a more pro-homosexual region may evoke or draw out homosexual behavior in young men. The implication is that some homosexual men who were reared in urban centers would not have become homosexual if reared in non-urban centers. The authors explain, "the environment in which people grow up affects their sexuality in very basic ways."

This map of the CA Prop 8 results would seem to support the "urban influence" findings.

For American women, the environmental factor most associated with a homosexual or bisexual identity was a higher level of education. And though that was also true for men, the pattern for women was more dramatic. For instance, a woman with a college degree was nine times more likely to identify herself as non-heterosexual than a woman with only a high school diploma.

For more information about the college education influence on homosexual determination, click here.

To read the entire Trayce Hansen research compilation with reference and source citation, click here.

15 comments:

In other news, research shows that people who had TVs at home were more likely to watch TV.

My understanding is that many things are a combination of both genes and environmental factors. You see the same thing in hereditary diseases. Just because you have the gene doesn't necessarily mean it will exhibit itself without some additional environmental factors. That doesn't mean that gene doesn't exist.

To prove your claim, you'd have to first isolate the genes expected to be responsible for homosexuality and then find that homosexuality also exists in people without those genes.

Well the gays are claiming that they can't help it because they were born this way. I have never heard one say it was environment. This study proves that they choose to be that way. Genes have little to none to do with it.

On the other hand, what an engenius way to study this, I would have never thought to use twins!!

This is really old news but I'm glad you posted new data confirming what we already know

Even prominent, homosexualist researchers of congenital causation factors for homosexuality have acknowledged:

"Despite common assertions to the contrary, evidence for biological causation does not have clear moral, legal, or policy consequences. To assume that it does logically requires the belief that some behavior is non-biologically caused. We believe that this assumption is irrational because … all behavioral differences will on some level be attributable to differences in brain structure or process. Thus, no clear conclusions about the morality of a behavior can be made from the mere fact of biological causation, because all behavior is biologically caused…. Any genes found to be involved in determining sexual orientation will likely only confer a predisposition rather than definitively cause homosexuality or heterosexuality."

Studies have shown that it is a cross-cultural (and cross-species) phenomenon that males find monogamy considerably more difficult than females (certainly due in part to high testosterone levels in males). Since men don’t ask to think about sex so often throughout the week and don’t ask to be sexually aroused by the sight of beautiful women whom they know nothing about, shouldn’t society dispense with the monogamy principle for men? Isn’t a “polysexual” orientation “as intrinsic to [most men’s] makeup as skin color”? It is certainly not a “choice.” So in light of this “new knowledge,” why not provide marriage benefits to persons in a committed polysexual relationship? Isn’t it better for a polysexual person to be in a committed relationship with each sexual partner than to engage in a series of one-night stands?

Again, studies on twins are necessary but not sufficient. Many genes are not an either or case. They merely raise the chance for you to become that way.

Identical twins do not always share the same interest, do not always look all that alike, and may not develop and die from the same old-age diseases.

Possibly the biggest problem with identical twins is that they are not actually genetically identical. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B8JDD-4RV1K19-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6dcb1bd33a25059afba51d1ac7267f75

While the twin studies may not be conclusive in and of themselves, the idea behind citing various studies that all point to a similar conclusion is to show that research tends to agree that biology is not the definitive winner in this homosexual causation equation.

And thank you to Fitz for reminding us that we ought not to be casually dismissing ideals and creating new laws in order to protect individuals' predispositions - whether these individuals make up a minority or a majority. This would certainly open up a can of worms.

Spot-on, Fitz. That is an important distinction. And it would appear that the pressure to either experiment with or adopt a lesbian sexual orientation is beginning now in high school (or perhaps even earlier). In addition to desensitization by the media, peer pressure is now a major factor in the embracing of and experimenting with homosexuality. A friend of mine who attends church with me has a daughter in high school here in California. I asked my friend how Prop 8 was affecting her daughter's high school experience and friendships. Her reply was chilling, "Oh it's already in schools. Girls walk through the hallways holding hands and boys in all their teenage maturity egg them on to kiss and make out. Girls who do not experiment with lesbianism, or feel the identity is wrong, are considered weird."

Definitely there's an edge factor in homosexual behavior. When we were at wave rallies, there were counter waves with kids who had no idea what they were doing, claiming to be all of these things just for the drama of it. Some you could tell it was from the heart and a true struggle, others, it was all about the next cool thing.

1. why do you assume that because something is environmental, you "choose" to act upon it? studies have shown that the people you are attracted to is set, for any person, by the time you are 8 years old. you don't "choose" who you are attracted to- it happens.

2. if people just want to be cool, and go with the flow, then why on earth would they "choose" to be gay?? it's hard!! there's prejudice. families tend to be angry. some friends will reject you. very few people decide to be gay merely because it's cool- to go through all that heartache, it has to be something you really feel.

3. i happen to know a set of twins, one who is happily in a civil partnership, and the other who i happily married to a man. the lesbian twin believes that her sexuality came, in part, from her mother's constant reliance on her, and this induced her to take a different role in the family than she otherwise might. why does this make her feelings any less real? so what if her sexuality was determined after she was born? feelings are feelings. love is love. why should she not act upon that love just because her genes didn't tell her to?

1. Studies do not definitively show that "the people you are attracted to is set, for any person, by the time you are 8 years old." Perhaps you could share with us the research you are citing? What the studies here show is that if environment plays a part in the development or rejection of a sexual orientation, then indeed it is not purely genetic as most gay rights activists claim.

2. Perhaps, as you say, regardless of nature v. nurture you don't choose who you are attracted to. It is still true, nonetheless, that you most certainly do choose whether or not to act upon those attractions. I do not believe it is a choice between being persecuted and being loved; more that homosexuals have to choose between self-indulgence and restraint. The first brings temporary happiness and the latter eternal happiness.

3. Interesting twin "story," but not a conclusive "study." This is why research studies are conducted on large sample sizes.

"why should she not act upon that love just because her genes didn't tell her to?"

Because we all sacrifice personal desires of some sort for the greater good of society. Calling black white can only result in misery and societal breakdown.

a woman falls in love with a man. he is very stupid. having children with him will result in these children being stupid, and this will contribute to "societal breakdown". should she not marry him, because of something he cannot control?

should a woman not marry a woman because, according to some, this will lead to a "break down of society", even though it does not seem like it will to her?

children deserve a mom and a dad. the only reason government cares about marriage is because of any children that may result. i'm not going to strip any child of that right.

The first situation you propose does not include a law or a change in a word definition. I would say, the decision is up to the woman.

The second situation does include a change in law and definition. The woman should not contribute to the weakening of marriage--because it undoubtedly leads to the breakdown of society. She should follow whatever is the law.

I don't understand how the joining of two women or two men who love eachother will contribute to this breakdown of society. If anything, i would imagine it will have the opposite effect.

- One of the main complaints about homosexual relationships in this column is that you seem to think that they all live risky sexual lives, and are not exclusive in their relationships. If marriages were introduced, with vows which included monogamy, exclusivity would be encouraged.

- Marriages lengthen relationships. That is a fact. If homosexual couples were allowed to marry, relationships would be fortified, and any children produced in the relationships (which there will be, marriage or not) will be protected against the pain of their parents splitting up.

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